The present invention relates to flooring materials and in particular relates to joints in certain types of polymer-based flooring materials that are used in non-slip (or “non-skid”) applications, sanitary applications, and applications in which both non-slip and sanitary characteristics are desired or necessary.
Certain structural elements in commercial or other public establishments must meet the requirements of various local, state or federal codes. For example, a restaurant is typically governed by local health and sanitation codes, and if it meets certain other criteria, may also be subject to state and federal health and safety requirements such the Occupational Health and Safety Act (29 U.S.C. § 651 et seq.) and related regulations such as (but not limited to) 29 CFR 1910.21-1910.30.
In most circumstances, a restaurant must be floored with a material that can be maintained at, or if necessary brought to, the highest sanitary standards. Additionally, restaurant flooring, particularly kitchen (or other food handling and preparation areas), should be formed of a material that helps prevent workers from slipping when the floor is wet or otherwise soiled with food or food preparation materials.
The concurrent requirements for high standards of sanitation and non-slip (non-skid) characteristics can be at odds with one another in certain structures. For example, some non-slip surfaces are prepared by mixing a polymer or paint with a solid (grit) material and applying the polymer in a manner analogous to painting to produce a surface with embedded abrasive particles. Non-slip flooring is also often produced by forming a three-dimensional pattern in the flooring material itself.
Alternatively, surfaces intended for sanitary use are often preferably as smooth as possible so that they can be easily cleaned on a frequent basis and so that they avoid structural elements that can trap dirt or other undesired items that can contribute to unsanitary conditions.
Typical materials for commercial kitchen flooring (although certainly applicable to residential areas as well) have included wood, concrete or cement, and ceramic and non-ceramic tile. Each of these offers certain advantages and disadvantages depending upon the particular circumstances.
More recently, polymer materials have become favored for these applications. As in many other circumstances, polymers are (usually) low in relative cost as compared to wood or ceramic tile, are widely available and offer a range of desirable properties.
Some of these polymer materials are available in pre-cured form, typically liquids. They are then applied using brushes, rollers or squeegee-type tools. Such pre-cured polymers can be applied to a wide variety of surfaces and because of their liquid form, need not be precut or otherwise dimension the cause they (like all liquids) simply take the shape of their container, which in this case is the floor.
As potential disadvantages, however, materials applied as liquids typically require a finite drying time, may produce undesired (or even regulated) solvent vapors, may not stick well to certain underlying surfaces and may require sophisticated priming or be limited to certain surface materials.
Accordingly, other polymers are available in cured sheets that can simply be positioned as desired all on a floor to be covered.
For example, certain vinyl (e.g. polyvinyl chloride or “PVC”) polymers can be easily manufactured into sheets or rolls of relatively large size (e.g., one quarter inch thick sheets of five feet by eight feet or rolls of the equivalent width and much greater length). Such sheets can provide cushioning surfaces (important to those who work on their feet for extended periods of time), that can be easily cleaned and maintained at the necessary sanitary standards, and that provide a greater grip in many circumstances then materials such as wood or ceramic tile. Examples of such material are set forth in U.S. Pat. Nos. 5,466,320 and 5,560,797 among others and commercially available materials are sold under the PROTECT-ALL® trademark (Oscoda Plastics, Inc. Oscoda, Mich., USA).
Because the polymer is manufactured and transported in sheet form (whether as discrete stacked sheets or rolls), the sheets in turn must be fitted to the particular flooring application. This may require cutting the sheets to fit particular floor designs and also connecting the sheets to one another in a manner that—where required—preserves the sanitary surface. Stated differently, merely placing individual PVC sheets on a floor does not complete the necessary sanitary arrangements because food can gather at the unsealed joints and in turn encourage the growth of unsanitary bacteria.
An appropriate joint should resist forces of tension, compression, shear, cleavage, and peel. These can be addressed through various structural arrangements, including joints with additional layers of reinforcing material. In flooring applications, however, joints that change the otherwise (usually) level flooring may be unacceptable. Thus, simple overlapping joints create a bump as do tapered overlapping joints, single or double strap joints, and tapered strap joints. Similarly, using profiles (i.e., additional structural pieces) to create the joint may be acceptable for some purposes, but can create a slight bump that is unacceptable in other circumstances. For the same reasons, the types of reinforced and U-shaped joints that can be used to connect metal sheeting in non-flooring applications are generally unacceptable for kitchen or other sanitary flooring. In addition to the bumps that they create, the bends and three-dimensional structures that they include can defines spaces that are hard to clean and that can provide a incubation point for bacteria.
Accordingly, when installing PVC flooring in a food service (kitchen) application, the individual sheets must are often welded to one another to form the joint. This is typically carried out by placing two sheets in abutting relationship, cutting a V-shaped channel that removes a portion of each abutting sheet (e.g. with a router) and then welding the sheets together using a PVC rod or bead while applying heat.
Although this technique has satisfactory applications, it requires both the routing and welding steps. Because the seams are abutting, they also have a tendency to separate or potentially fail, leading to some of the safety and sanitary problems described above.
Accordingly, a need exists for improved methods of joining such polymer-based flooring in food service and related applications.